1. Field of the Invention
The present invention relates generally to switching devices, and particularly to electromechanical switching devices.
2. Technical Background
A single pole single throw (SPST) switch is an electrical device that is an ON/OFF switch in that it either allows current to flow through a circuit or it interrupts that current flow. Wall switches are often configured as SPST switches that are used to turn electrical loads (such as lights) ON or OFF. Thus, when a person enters a darkened room they actuate the switch to turn the lights ON, and when they leave that room, they turn the lights OFF.
A single pole double throw (SPDT) switch, on the other hand, may be used to divert current from one circuit path to another circuit path, and vice-versa. When this type of switch is used to control lighting loads, it is often used in tandem with another SPDT switch such that the lights can be turned ON or OFF from two different locations. For example, one often finds one SPDT switch at one end of a hallway and a second SPDT switch at the opposite end of the hallway. Thus, the arrangement allows the person to turn the lights ON, traverse the hallway safely, and then turn the lights OFF at the other end of the hall. Both the SPST switch and the SPDT switch are commonly implemented as electromechanical switches that employ moving mechanical parts to make or break the electrical switch contacts.
In reference to FIG. 1A, a simplified view of a pendulum-type toggle switch 1 is shown. This type of device usually employs a paddle switch (not shown) that is used by the operator to throw the switch into the desired state. Paddle switches exhibit a relatively small amount of rotation (e.g., less than 10°) and can be actuated with a touch of the finger. Accordingly, many consumers find them convenient and easy to use. As shown herein, switch 1 includes two traveler terminals 2, 3 and a switch actuation pendulum 4 coupled therebetween. The switch pendulum 4 typical rests in a cradle that is connected to line hot. Thus, if one traveler is connected to the premise wiring the switch implements a SPST switch; however, if both travelers (2, 3) are properly connected to premise wiring, then the switch 1 operates as a SPDT switch because operation of the switch diverts current from the hot line to either traveler 2 or traveler 3. When a user depresses the switch paddle (not shown), a force greater than the make force of spring 5 is applied to drive the pendulum contact from engaging traveler contact 3-1 to engaging the opposing traveler contact 2-1. When the pendulum contact 4-1 strikes the opposing traveler contact 2-1, the closing of the contacts (2-1, 4-1) creates a loud noise that some consumers find annoying. Stated briefly, many consumers like the convenience of the paddle switch actuator but do not like the associated noise. Hence, one drawback to the switch mechanism depicted in FIG. 1A relates to the loud actuation noise it produces when the pendulum contact strike the traveler contact.
Referring to FIG. 1B, a cross-sectional view of a toggle switch 1′ is disclosed. Toggle switch 1′ is shown to include a toggle switch actuator 6 that has an axis of rotation about the trunion 6-3. The switch 6 also includes a cam element 6-1 that extends from the trunion 6-3. In FIG. 1B, the cam element 6-1 is pressing against the traveler contact arm 2-2 such that contacts 2-1 and 3-1 are open. In doing so, the toggle actuator 6 is rotated an amount θ/2, wherein θ can be as much as 40-60°. Because the toggle actuator 6 rotates approximately 40-60° when moving between switch positions, the spring force associated with spring 5′ is relatively high. Thus, the switch contacts (2-1, 3-1, and 4-1) are relatively quiet. Nonetheless, because the toggle switch actuator must rotationally move such a large distance (i.e., about 40-60°), a user must purposely hold the toggle switch between their thumb and forefinger and rotate the toggle switch actuator in order to change switch states. More often than not, users are in a hurry and simply bend their index finger and snap their wrist in a single motion to actuate the switch. When this happens, a relatively large force is applied to rotate the toggle actuator and it often causes the flat bottom portion 6-2 of the toggle switch actuator 6 to loudly strike the portion of the switch housing under it. Even though the contacts are relatively quiet, the sound advantage is nonetheless negated. Thus, the drawbacks associated with this switch type relate to the large angle of rotation between switch positions and the loud noise that is sometimes associated with actuating the switch.
Heretofore, the solution to the above stated problems was to employ a switch mechanism that uses an electronic switch actuator, such as a push button switch. A push button switch can be operated with a flat push actuation plate or with a paddle switch actuator. Moreover, the push button switch makes substantially no noise when it is actuated. However, there are drawbacks associated with electronic switches. Electronic switches are relatively expensive and not as robust as electro-mechanical switches. Accordingly, electronic switches are not as reliable and must be replaced more frequently than electro-mechanical switches.
Turning now to another consideration, there are several drawbacks associated with conventional installation methods and conventional protective electrical wiring devices. Conventional protective electrical wiring devices often do not make efficient use of space. In addition, mounting the wiring device's ground strap to the device box is tedious, time consuming, and therefore costly. The same can be said of mounting the cover plate to the electrical wiring device. Moreover, in multi-gang installations, the finished look is often ragged because the plurality of electrical devices and their respective cover plates are typically not in alignment. This misalignment can be, and very often is, in all three dimensions. Retrofitting an electrical installation can also be problematic from the standpoint of the finished look because the device box, or an old work box, may not be precisely aligned to the plane of the wall surface. This is especially true if the wall surface itself is uneven. After remodeling a space, homeowners often seek to replace an existing wall plate with one that better matches the new décor. Thus, a homeowner may inadvisably remove the faceplate cover from an energized wiring device and inadvertently become exposed to a shock hazard from the “hot” electrical wiring.
What is needed, therefore, is an electromechanical switch mechanism that obviates the drawbacks articulated above. In particular, what is needed is an electromechanical switch that is substantially quiet and easy to operate, having a small angle of rotation between switch positions. A switch of this type is also needed that can be employed in a number of different form factors including one suitable for use in a modular framing system such that it does not require fasteners to be securely installed within the device box.